1. Field of the Invention
The present invention relates to circuit interrupters generally and, more specifically, to those kinds of circuit interrupters having a cradle that rotates in the event of a tripping operation.
2. Description of the Prior Art
Molded case circuit breakers and interrupters are well known in the art as exemplified by U.S. Pat. No. 4,503,408 issued Mar. 5, 1985, to Mrenna et al., and U.S. Pat. No. 5,910,760 issued Jun. 8, 1999 to Malingowski, et al., each of which is assigned to the assignee of the present application and incorporated herein by reference.
Circuit interrupters typically include an operating mechanism structure, sometimes termed a "cradle", that is disposed in the interrupter housing and which rotates from a first position to a second position in the event of a tripping operation. A pivot pin is rotatably disposed in the housing and through the cradle in order to provide for such cradle rotation.
In the prior art, it is known to weld the cradle pivot pin to the cradle. It is also known to spin (like a screw) or stake (forcibly press) the pivot pin to the cradle. Unfortunately, these prior art methods do not enable the pivot pin to be heat treated for strength. This is because such a treatment, applied before the pivot pin is connected to the cradle, would make the pin too susceptible to damage during a welding, spinning, or staking process, each of which requires a large amount of force and/or stress to be applied to the pin. In addition, the prior art methods do not enable the cradle to rotate if the pivot pin somehow binds and cannot rotate. Furthermore, the prior art methods do not enable the pivot pin and cradle to be conveniently disassembled after connection.
It would be advantageous if a way existed to effectively connect a pivot pin to a cradle that would still enable the pivot pin to be heat treated. It would also be advantageous if such a way enabled the cradle to rotate even if the pivot pin did not, and enabled the pivot pin to be disassembled from the cradle in a convenient fashion.